Many posts around the world are seeking to develop a more effective mail merging system that automatically merges all mail streams and sorts them to as fine a degree as time permits, preferably to delivery sequence. The system should accomplish this merging at the step of carrier sequence sorting by merging all elements of the mail stream (letters, flats, periodicals, post cards etc.) at some point during the sorting process.
At present, some of the mail streams arrive at the postal branch offices sorted in delivery sequence and some do not. Generally, even when the mail arrives at the branch already sorted to delivery sequence, postal carriers need to merge multiple streams of mail (often as many as ten streams) from different mail trays—and for this, the postal carriers generally use a manual sorting process. When mail does not arrive at the branch already sorted, the carriers spend even more time—several hours—sorting the mail into carrier delivery sequence manually. Often, the carrier on mechanized routes will complete the mail merging while sitting at each post box—merging mail from multiple mail trays on the spot before placing it in the mailbox. This requires carriers to spend substantial time merging and sorting the mail before they can start to deliver it, or else they must complete the merging while they are delivering the mail, thus making the mail delivery process (the last mile) quite inefficient.
In 1990, the United States Postal Service (USPS) issued a Request for Proposal for a carrier sequence bar code sorter, type B, a single pass sorter to arrange mail in carrier delivery sequence. To date, 16 years later, no product has yet been manufactured and delivered to satisfy that need.
The 2003 Presidential Commission Report on the Future of the United States Postal Service (USPS) concluded that the Postal Service should continue to develop an effective merging system that is responsive to customer needs and culminates in one bundle of mixed letters and flats for each delivery point. The system should accomplish this merging at the step of carrier sequence sorting by merging all elements of the mail stream (letters, flats, periodicals, post cards etc) at the final sorting process.
The USPS sometimes does delivery sequence sorting at central sorting facilities. The sorting is done there because the equipment required to automate this process is simply too large to fit in the branches. The cost would be prohibitive for the USPS to install such equipment in each branch. Furthermore, sorting centrally is also much more efficient, since the only sorters available today are multiple pass sorters which may include over a hundred bins and may require two or more sort sequences to get the mail in delivery sequence order. However, when the carrier delivery sequence sorting is done centrally, and then sent to branch offices, the carriers usually spend the first two to three hours of their day merging sorted mail with other unsorted mail, much of which was shipped directly to the branch offices by publishers to receive discounts on postage, and sorting it all to delivery sequence. For many places in the postal network (especially outside the USA), mail is still sorted by the carriers manually, placing each piece in a slot with a designated address to sort the mail into delivery sequence.
The sorters available on the market today have significant limitations: they are either huge, expensive pieces of equipment with a very large number of bins, and require significant space to operate; or they have a smaller number of bins, but require multiple passes to operate. This multi-pass operation is a very labor-intensive process. So, for example, a sorter with 16 bins, sorting a job with 2000 mail pieces, will require three passes to sort to delivery sequence for 600 address on a route. That means the operator must load the mail, operate the sorter, then unload the mail from each bin and re-load it into the feeder three times. While this results in some time savings compared to manual sorting, the value proposition is limited because of the high labor content. See, for example, U.S. Pat. No. 6,555,776 entitled “Single Feed One Pass Mixed Mail Sequencer,” filed 2 Apr. 2001 and issued 29 Apr. 2003.
It is because of the high labor content still required with high speed, multi-pass sorting equipment that postal services such as the USPS, Swiss Post, and Royal Mail have requested proposals for a single pass system that can merge all mail together before it is sorted to delivery sequence. Likewise, the manual method is still the most common method that enterprises use to sort their incoming mail; this is also very labor intensive, but the investment required and the size of available mail sortation equipment is generally prohibitive.
The following two U.S. provisional patent applications are incorporated herein in their entirety: Application No. 60/589,634 (filed 21 Jul. 2004), and Application No. 60/634,014 (filed 7 Dec. 2004). The first of those two provisional applications (Ser. No. 60/589,634) provided a basis for U.S. Regular Patent Application Serial No. 2005025846 filed 21 Jul. 2005; and U.S. Regular Patent Application Serial No. 2005025899 filed 21 Jul. 2005; and also U.S. Regular Patent Application Serial No. 2005025634 filed 21 Jul. 2005. The second of those two provisional applications (Ser. No. 60/634,014) provided a basis for U.S. Regular Patent Application Serial No. 2005044560 filed 7 Dec. 2005; and U.S. Regular Patent Application Serial No. 2005044406 filed 7 Dec. 2005; and also U.S. Regular Patent Application Serial No. 2005044413 filed 7 Dec. 2005. Those two previously filed U.S. provisional patent applications describe various aspects of a full escort sorting system. Using such full escort sorting systems provides benefits such as the following:                1. All mail can be sorted to delivery sequence in a single pass, a pass being defined as one cycle of operator loading into the sorter.        2. The full range of mail can be handled including cards, letters, flats, periodicals, publications, newspapers, and parcels up to 25 mm thick.        3. The sorter operates at very slow speeds (0.05 m/sec compared to the 5.0 m/sec for competitive sorting speeds)—but can complete equivalent jobs in less time than competitive sorters.        4. Each mail piece is touched only once. After it is fed and read, each mail piece is put in a clamp, and the sorter interacts only with the clamp throughout the entire sorting operations. (Note that the present invention is, of course, not limited to clamp-based sorting systems, and can work with conventional sorters as well.)        5. Automated unloading algorithms eliminate the need for an operator to “sweep” the sorter (sweeping refers to manually unloading the sorter).        6. The sorting stations can be modular—so that the sorter can be configured as large or as small as needed, and can be adapted to the customer's existing facility. The sorter uses vertical space to reduce footprint.        7. The sorter can be operated with one or two operators in a centralized application, compared to five to eight operators for competitive equipment.It is noted that the clamp arrangement just mentioned (at item 4) is similar in a limited sense to an invention of Catherwood, disclosed by International Application PCT/GB02/05203 with International Filing Date on 19 Nov. 2002. In Catherwood, however, it is required to attach self-adhesive tape to mail pieces, unlike in the two previously filed U.S. provisional patent applications.        
Centralized sorting centers such as the USPS facility at Wallingford, Conn., USA, process inbound mail during one or more shifts and outbound mail during other shifts within a 24-hour period. Inbound mail is mail collected locally plus mail sent from other sorting centers intended for sorting and delivery within the area served by the centralized sorting center. Outbound mail is mail collected locally, destined for other sorting centers.
The Wallingford sorting center operates around the clock in three shifts, and handles mail volumes of 5.5 million letters and about half a million flats every 24 hours. Separate pieces of sorting equipment are required for letters and flats, and at least 20% of the mail cannot be sorted by machine and must be sorted by hand.
To accomplish this level of volume, Wallingford currently has 25 pieces of sorting equipment, operated by 72 operators each shift. The specific equipment is as follows:                18 Delivery Bar Code Sorters (DBCS) with 206 bins for delivery sequence sorting of letters, 40,000/hour, 2 operators        3 Bar Code Sorters (BCS)—only reads bar code, 100 stackers, 2 operators        3 FS100 for flats, requires 5 operators, 15,000-18,000 flats per hour, 3 feeders        1 FS1000 for non-machinable flats: 5 operators        Newspapers sorted manually, probably 8-10 clerksThroughout this application, a “bin” refers to a sorted mail station, and a “feeder” refers to a feeding station.        
In addition, some areas of Wallingford are equipped with a tray handling, storage, and retrieval system to move trays of mail from point to point. However, much of the tray storage and transporting is still done manually by postal employees pushing trolleys full of mail trays by hand.
Impressive as the Wallingford sorting operation is, there are several weaknesses in the current system, such as the following:                1. Dozens of employees are required to simply move mail onto and off of trolleys, and move the trolleys from one point to another point in the facility multiple times.        2. Each mail piece must be loaded onto a feeder belt so it can be fed into a sorter, and then unloaded from the sorter multiple times during the sorting process.        3. Each trip through the sorter involves risks that the mail will jam, or be damaged by the automated processing equipment. Typical operating speeds for the mail in a sorter are over 200 in/sec (5 meters/sec), which is so fast that the mail appears as a blur. It is not uncommon for any single mail piece to go through one or more mail sorters 4 to 6 times. Each of these trips through the sorter increases the risk of jams or damage.        4. Despite the large investments in automation, a relatively high proportion of the mail is still considered “non-machinable.” Currently, about 20% of the letter mail cannot be sorted automatically. An equivalent percentage of flats will probably be considered non-machinable once the next generation of flats sorting equipment is installed. This mail is still manually sorted to route and then manually sorted again—to delivery sequence—at the DDUs (Destination Delivery Units, or local post offices where the mail carriers report to work). These manually sorting steps are a time consuming and costly process. Despite the high investments in automation, each mail carrier still spends between 2.5 and 3 hours each day manually sorting the mail that could not be sorted by machine. This step alone costs the USPS about $3 Billion each year in labor costs.        5. There are a number of operations that are still done manually at Wallingford because the mail cannot be handled by the automated equipment. Newspapers, periodicals, flyers, and some magazines fall into this category. Again, the manual operations are the most costly in the sorting operations.        6. The sorting equipment has limited capacity and a finite number of pockets—which is the reason mail must be run through the sorters multiple times. Typically, the sorters are operated in different modes at different times of the day. So, during one shift, only outbound mail may be sorted. Any mail for the area served by Wallingford is identified during the sorting process, and set aside for sorting further during a later shift. A second shift might then be used to sort the inbound mail to zone. The mail is sorted again—to route. Mixed in with these sorting processes is the “local” mail that was set aside during the first shift sorting. Then, the third shift might re-sort all of the mail sorted during the second shift—this time sorting to delivery sequence. The sorters must be set up to operate with these different sorting algorithms—and the sorted mail must be unloaded, stored, then later made available for re-loading into the sorter for subsequent sorts. This not only requires a lot of labor, it also requires a lot of floor space for storing the mail.        7. The 25 pieces of sorting equipment and the space around them to store trays of mail for processing multiple times all requires a huge footprint. The attached sketch approximates the floor space required for the 25 pieces of sorting equipment at nearly 70,000 square feet of floor space. The cost of real-estate, heating, maintenance, etc. must also be considered in the cost of processing the mail. If this space could be reduced, the cost per mail piece for sorting will similarly be reduced.        8. The sorting equipment tends to be dedicated to a single type of mail piece. Separate systems are required for sorting different types of mail: some sorters sort only letters and others sort only flats. If a greater than normal volume of one type of mail occurs on any particular day, there is no opportunity to divert some of that mail processing to a sorter designed to handle only the other type of mail. So, the managers have limited flexibility in how they use the equipment.        
So, while the automated sorting operations at Wallingford are quite impressive in the degree of efficiency and sophistication, there remain numerous opportunities for improving the efficiency of the operations even further. Wallingford is used only by example. All of the 387 Wallingford-like sorting centers within the USPS network, and the thousands of Wallingford-like sorting centers in other postal systems around the world, would greatly benefit from increased efficiencies.